In response to PAR-07-004: "Community-Based Participatory Research at NIMH," we propose a 2-year proof- of-concept study (R21) to develop, implement, and evaluate a culturally relevant intervention to increase HIV testing among gay and bisexual men and men who have sex with men (MSM) who use Internet chat rooms for social and sexual networking. Building on our established community-university partnership and our preliminary research using chat rooms to deliver HIV prevention and outreach interventions, we will develop, implement, and evaluate Chat Room-Based Education and Referral/Testing (CyBER/Testing). This study has used and will continue to use a community-based participatory research (CBPR) approach throughout all phases of the research process. Our partnership will determine whether a chat room-based intervention can be successfully implemented and increase HIV testing among chat room MSM. The intervention will be based on social cognitive theory and the theory of empowerment education. We will evaluate the intervention by: (1) Comparing HIV testing rates among MSM in intervention counties before, during, and after intervention implementation;(2) Comparing HIV testing rates among MSM in intervention counties to HIV testing rates among MSM in comparison counties;and (3) Comparing self- reported HIV testing among MSM in the intervention chat room before and after the intervention. Our endpoints will be whether the intervention increases HIV testing among MSM using (1) longitudinal time series data to examine HIV testing data at the county level, and (2) repeated cross-sectional self-reported HIV testing data among chat room MSM. We also will evaluate the CBPR process throughout all phases of this study, using direct observation of partnership meetings, in-depth interviews with partnership members, and document review. This study will advance the field of HIV prevention research and fill existing gaps in knowledge in 3 important ways: (1) producing a culturally relevant chat room-based intervention to increase HIV testing among men at increased risk for exposure and transmission, which then can undergo further implementation and larger-scale testing;(2) promoting a deeper understanding of HIV testing behavior among MSM who use Internet chat rooms;and (3) elucidating a research partnership process that includes lay community members, AIDS service organizations (ASOs), community-based organizations (CBOs), 3 universities, and a broad spectrum of other partners. Chat room-based HIV prevention interventions are being implemented to reduce the risk of HIV exposure, infection, and re-infection among men who have sex with men (MSM);however, the use of these chat rooms to facilitate HIV testing among these at-risk MSM has not been tested. This study, which was designed by an existing community-university partnership committed to HIV prevention and care, will explore whether a chat room-based intervention can increase HIV testing rates among online MSM.